Strabismus — Is Surgery Enough?

The following excerpt is from a blog piece which I guest-authored. It was originally published on the COVD Blog site in February, 2011.

Eye turns are a common problem affecting about 3% of the population.

Often, when patients with eye turns come to me, they are not aware of any non-surgical options to address their problem. Some of these patients have already had surgery, perhaps unsuccessfully, or they report that the surgery worked for a while, but “didn’t hold.” They’ve often been told in advance that they may need a second or third surgical procedure.

The problem with treating an eye turn (strabismus) with surgery alone is that strabismus is rarely a “muscle-only” problem. Especially after years of living with the eye turn, our highly adaptable brains come up with strategies for coping with information coming from two eyes which do not point in the same direction.

Please click the link below to view the full blog piece, along with the host of comments which follow!

2 comments on “Strabismus — Is Surgery Enough?”

Intriguing read and an even more intriguing reaction to such a read. You’re clearly a passionate doctor. I have some specific questions about the blog post, but also some specific questions about my case of esotrpia.

1. Could you more specifically define anomalous projection? I can interpret it in two ways: #1 the eyes are taking information from different spots in the retina to send to the brain to make make the best 3d image possible, or #2 the eyes are taking info from the same spot in the retina (as the other eye) to send to the brain, but also use info from the entire visual field to create the best 3d image possible?

I’ve uploaded an illustration to show normal correspondence and these two possibilities. Please let me know if the link works. Is #1 or #2 correct?

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“Now consider what would happen if the eyes were made to align (surgically), but anomalous projection continued to match up information between the two eyes based on the way they had been positioned for years up until the surgery. In many of these cases, the patient begins to see double after the eyes have been re-positioned.”

2. Is anomalous projection something that can be detected using prisms or prism glasses? How would one know for sure if they’re suffering from anomalous correspondence?

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“In many of these cases, the patient begins to see double after the eyes have been re-positioned. Even worse, these patients may experience visual confusion. Visual confusion is the appearance of two different objects overlapping, as if they come from the same place. The brain now has the same two main options for avoiding visual confusion: suppression and anomalous projection. Since anomalous projection worked successfully before, these patients may learn to re-assign information based on their new eye positions.”

3. Let me get this straight, you’re saying that IF the eyes/brain were using analogous projection before surgery, once the eyes are made to align the person will see a double image, basically as soon as they wake up? In other words, if the person doesn’t have anomalous projection, they will not see double when they wake up (at least not as a result of anomalous projection before surgery)? They will also NOT be at risk of experiencing visual confusion?

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I developed esotropia when I was 6 years old. My left eye was pretty much turned all the way in. Surgery on my left eye corrected it and I’ve always had 3d vision and been able to see 3d movies pretty well. I’m right eye dominant. I developed esotropia again for unknown reasons at age 27, I started off measuring 6, went up to about 35 within 9 months, and hover now around 30. I’m now 30 years old and have had it for about 3 years. I had problems with my insurance and was not able to see a doctor for over a year, but now I’m back. I have prism glasses that the surgeon wants me to wear for a few weeks to see if surgery would be appropriate. They seem to be working.

I have enough fusional amplitude to fuse an image within arm length, but not any further. It gets worse and worse the further I look. Most of the time I can see the 3d slides they show me up close, but, since I see completely double at distance, I can’t see anything 3d with the 3d glasses. I spend most of my time looking at things close to my face because looking out in the distance is uncomfortable and strains my eyes, making it harder to fuse up close.

People tell me they can’t even see my eye turning in up close, but they can if I’m far away.I personally don’t think I’m suffering from analogous projection.

4. My question is, do you believe I could have analogous projection?

5. What is the possibility that I would benefit from vision therapy? Could you point me to a visual therapist in the Chicago area who is highly skilled and as passionate as you are?

6. Also, what other known reasons are there for esotrpia to reoccur after surgery aside from suppression and anomalous projection? Are there unknown reasons it can reoccur?

7. How long should a person wear prism glasses to show that they can consistently fuse the image at all distances before having surgery? Is this a determining factor that the surgery would hold?

Dear Rick,
I have replied off-line to some of your questions.
I appreciate that you have put a lot of thought into this.
Fortunately, your brain has been primed for binocular seeing (whether with the support of AP, or with NP… one could not say without evaluating you).

I think it is important that you fully investigate whether there are any anatomical or pathological explanations to the re-emergence of your eye turn. This should be evaluated before considering surgery.
I have made some referrals, privately.

Anomalous Projection is the brain’s way of re-processing space as transferred via the two eye-channels so that s/he can regain some trust that the world they SEE will match the world they TOUCH.

Corresponding retinal points may change, depending on the object location in space. It is not as simple as a “visual direction 30 degrees to the right of straight ahead” for example. The corresponding points will change depending on the distance of the object from the eyes.

Remember, 3-D images are never emerging from a single spot or point. DISPARITY is needed for 3D, which implies multiple object/image planes. What you stated as “#1” is closer to the truth… in the best case scenario: “the eyes are taking information from different spots in the retina to send to the brain to make make the best 3d image possible.”

But again, it’s the BRAIN gathering simultaneous information from different receptive fields on each eye.

Consider the eyes as the hardware, and that the brain can run different software programs to reprocess the data gathered via the hardware. AP is an alternative software program.

Vision is learned. It can be re-learned.

So, I cannot tell you what will happen post-surgically. I can only address potentials, prognoses, and work pre-surgically to assure a more likely positive post-surgical outcome.

And, in some cases, enough progress is made in the therapy process that surgery is not needed.
Hope this is helpful in your quest.
Sincerely,
Dr. Slotnick